Here are some links to get you started:
http://members.aol.com/americacruising/aiww-south.html
http://members.aol.com/americacruising/giww-west.html
http://www.toad.net/~tdove/icw.html
http://www.icw-net.com/
I just finished about 400 miles from Southport, NC to the Rappahannock river on the Chesapeake. Great trip.
Some general observations:
Carry a current ICW chart book.
Make sure your engine is in good shape.
Make sure your depth sounder works.
If your draft is over 6'' it will be tough and tedious.
Expect to touch bottom more than once.
Join TowBoatUS in case you go hard aground or need help.
I carried my mast on deck. I only had to deal with two bridges. This for me is the only way to go.
As far as cost, the major points are:
Marina fees
Fuel
Food
Unexpected repairs/towing
Shopping

Boat Preparations
If you''d like more details email me at mrb2222@yahoo.com
Mike